This invention relates to guide bushings and more particularly to such bushings of the rotary variety.
Bushings are commonly employed for guiding and piloting rotary tools in repetitive production processes. Most commonly, bushings for drilling, boring, reaming, etc. are fixed relative to their holding or supporting fixture and the tool or spindle. Because of the heat and wear resulting from vibration and friction between the tool and the bushing, such bushings are generally made of hard alloy or special steels or even lined with carbide materials which makes them relatively expensive. The fixed bushings also generally require the use of liquid coolants for lubrication and to dissipate some of the heat generated between the tool and bushing. In spite of their fabrication from special and expensive materials and the use of coolants, the fixed bushings render tools relatively short-lived and are themselves relatively short-lived.
An alternative to the fixed bushing is the rotary bushing wherein the bushing is mounted in a ball, roller or needle bearing and is allowed to rotate with the tool. Even here, however, considerable heat and wear results between the tool and bushing due to relative movements vertically and upon acceleration and deceleration of the tool.
It is generally an object of this invention to rotationally lock the tool and rotary bushing together to preclude relative rotation therebetween and thereby minimize problems resulting from heat and wear. Such an interlock therebetween greatly extends the life of the tool and the bushing without special cooling and even when the bushing is fabricated from less expensive and/or softer materials.